1. Field of the Invention
This invention relates to a host-vehicle risk acquisition device and a host-vehicle risk acquisition method that acquire a degree of collision risk between a host-vehicle and an obstacle, such as another vehicle
2. Description of the Related Art
A risk acquisition device is available that detects an obstacle around a host-vehicle, determines possibility of collision between the obstacle and the host-vehicle, and outputs the possibility of collision as a degree or risk. For example, a collision avoidance device uses such a risk acquisition device. When there is a possibility of collision between the host-vehicle and an obstacle, the collision avoidance device notifies the driver of a collision risk, or automatically performs deceleration control of the host-vehicle to avoid collision. (See, e.g., Japanese Patent Application Publication 7-104062 (JP-A-7-104062).)
However, the collision avoidance device described in JP-A-104062 calculates only one predicted path of the obstacle, when the obstacle is a mobile object, such as another vehicle. Thus, when the host-vehicle or another vehicle is running on the road where many paths of obstacles are expected, such as an intersection, it is difficult to calculate the possibility of collision, and the accuracy of the degree of risk may be decreased in the case where the degree of risk of the host-vehicle is calculated based on the possibility of collision.
Further, when the degree of risk of the host-vehicle is calculated, the degree of risk of the host-vehicle in the current state can be calculated; however, the degree of risk of the host-vehicle in the other travel states may not be calculated. Thus, the safety degree of the host-vehicle in the other travel state may not be determined.